Cellular communication devices use network radio access technologies to communicate wirelessly with geographically distributed cellular base stations. Long-Term Evolution (LTE) is an example of a widely implemented radio access technology that is used in 4th Generation (4G) communication systems. New Radio (NR) is a newer radio access technology that is used in 5th Generation (5G) communication systems. Standards for LTE and NR radio access technologies have been developed by the 3rd Generation Partnership Project (3GPP) for use by wireless communication carriers.
A communication protocol defined by the 3GPP, referred to as Non-Standalone Architecture (NSA), specifies the simultaneous use of LTE and NR for communications between a mobile device and a communication network. Specifically, NSA uses dual connectivity, in which a user equipment (UE) uses both an LTE uplink and an NR uplink for transmissions to corresponding 4G and 5G base stations. The LTE uplink is used for control-plane messaging and for user-plane communications. The NR uplink is used for additional user-plane bandwidth.
When using NSA, the sum of LTE and NR uplink transmit powers is legally regulated to be no greater than a regulatory maximum transmit power